1. Field of the Invention
The present invention relates to a plug pin, a position pin, and a plug pin set of a zipper; in particular, the present invention relates to a plug pin, a position pin, and a plug pin set of a double opening zipper that allows the plug pin and the position pin to be plugged and lifted smoothly.
2. Description of Related Art
Zippers are popularly applied to leather bags and clothing and can be easily operated. The principle of zippers is in that two zipper belts can be toothed to each other, and the two zipper belts are controlled to be opened or closed by pulling the zipper head back and forth. The material of the zipper belt and the zipper head can be metal, nylon, or plastic steel, etc.
Reference is made to FIGS. 1 and 2, which show the double opening zipper of the prior art. On the first zipper belt 10a and the second zipper belt 11a, there is a first zipper head 12a and a second zipper head 13a so that both ends of the first zipper belt 10a and the second zipper belt 11a can be controlled to be opened and closed. One end of the first zipper belt 10a and the second zipper belt 11a respectively has a position pin 14a and a plug pin 15a. 
The first zipper head 12a and the second zipper head 13a can be assembled on the first zipper belt 10a in advance, and the two zipper heads 12a and 13a are blocked and positioned by the position pin 14a located at one end of the first zipper belt 10a (as shown in FIG. 1). Next, the plug pin 15a located at one end of the second zipper belt 11a passes through the sliding trough in the first zipper head 12a and is plugged into the sliding trough in the second zipper head 13a (as shown in FIG. 2). Thereby, the first zipper head 12a and the second zipper head 13a are assembled on the first zipper belt 10a and the second zipper belt 11a, so thereby the first zipper belt 10a and the second zipper belt 11a may be toothed to each other can then be closed and opened by pulling the first zipper head 12a and the second zipper head 13a back and forth.
However, the position pin 14a and the plug pin 15a are fastened on the first zipper belt 10a and the second zipper belt 11a by punching the fastening point. The fastening point are punched and formed on one side or two sides of the position pin 14a and the plug pin 15a so that one side of the position pin 14a and the plug pin 15a that are adjacent to each other is extruded and protruded due to punching. The protruded may interfere with the first zipper head 12a and the second zipper head 13a so that the position pin 14a and the plug pin 15a cannot be smoothly plugged and lifted.